Snap switch



April 5, 1949. l.. FERNANDEZ-CASTRO 2,465,165

SNAP swITcH Filed March 14, 1947 INI/EN TOR.

Patented Apr. 5, 1949 UNITED STATES GFFlfCE Lizandro Fernandez-Castro, San Francisco, Calif.

Application March 14, 1947, Serial` No. 734,720v

1 Claim.

This invention relates to a snap action switch especially adapted for use in re alarm circuits, and more specifically to a switch of the character described which is actuated by a thermostatic element.

It is well known that numerous people have lost their lives in re due to the fact that the spread of re throughout a building had been so rapid that there had been no time to escape. It is obvious that most fires before reaching such proportions have been burning for some time and spreading undetected before reaching un* controllable proportions. If fires of this character were detected in their early stages by a positive alarm device of some Character, many lives and much property would be saved.

It is recognized that electrically operated alarms of diiferent types have been employed for this purpose but collection of dust over long periods of time, corrosion, oxidation of the contacts, etc. have caused many devices, even though they operated, to fail to give an alarm as the electric circuit through the contacts has not been completed.

The object of the present invention is to eliminate Iall factors of failure of electrical contacts; to provide a switch, one contact of which is pointed suciently to dig into the surface of the other contact and thereby insure a good electric circuit contact when the contacts of the switch engage; to provide a switch in which the contacts close with a snap action of considerable force; to provide a switch which is actuated by a thermostatic element; and further, to provide a switch which is simple in construction which may be quickly and readily adjusted to release the snap action contacts and close an alarm circuit the moment a predetermined temperature is reached.

The switch is shown by way of illustration in the accompanying illustrations, in which:

Figure 1 is a perspective view of the switch;

Figure 2 is a perspective view of the trigger lever;

Figure 3 is a perspective view of the bi-metallic thermostat arm; and

Figure 4 is a perspective view similar to Figure 1 showing the switch only, and in closed position.

Referring to the drawings in detail, and particularly Fig. 1, A indicates an elongated base or suitable support constructed of insulating material upon which is secured by screws I6 and I8 a clamping plate 2 and a iieXible steel spring arm 3, said arm having a contact 4 at its outer free end which is pointed, for a purpose hereinafter to be described. Also secured on the base or supporting member A is a plate 5 in which is mounted a contact member 5a and a terminal screw l. The screw IS is also a terminal screw, and wires 'la and IGa are connected to the terminal screws 'I and I6, respectively. The arm 3 and contact il when in engagement with the contact 5 close a circuit through the wires 'Ia and Ita, and this circuit may form a portion of an electric actuated alarm circuit or the like. The base member is in this instance supported by `a frame comprising a channel shaped member having a web I and anges Ia and 2a. The member A is secured to the flange la and supported thereby, and the remaining mechanism is supported by the web I. This mechanism comprises a pivot pin IU on which is lpivotally mounted a trigger consisting of two parallel arms 3 and 8b (see Fig. 2). These arms terminate in shoulders 8c whereby the end of the spring switch arm 3 is engaged. The trigger member has a rearwardly extending arm I3 and this is engaged by a bhmetallic thermostat arm I I which is supported by a bracket II and secured thereto by a clamping plate I2 and screws I4b. The arm Il is slotted longitudinally as shown in Fig. 3 at Ida. The screws Mb extend therethrough and arm II may thus be adjusted to bring it closer to or further away from the pivot point of the trigger member 8. Graduations are formed as indicated at hi on the arm II and also on the surface of the rear portion I3 of the trigger. Hence, by loosening the screws I4b and adjusting the arm II with relation to the graduations on the trigger, it is possible to set the switch `as a whole so that the trigger will release the spring arm 3 when a predetermined temperature is reached.

If the switch as a whole is to be used in a re alarm system, it is obvious that one or more of the same will be placed at points where heat is most liable to accumulate. The temperature at which the trigger releases the spring arm 3 may for instance be F., thus if a re were started and heat were rising therefrom, it would gradually accumulate around one or more of the switches shown until a temperature of 150 F. were reached. When that temperature is reached, arm II will bend sufficiently to swing the trigger about its pivot Il] to a point where the free end of the spring arm 3 is released. The moment it is released, the pointed end of the contact 4 will swing towards the contact 5 with considerable force and velocity, and will therefore dig into it sufcently to establish a clean and good contact thereby insuring a circuit through the terminals I6 and 1 which will insure operation of the alarm circuit.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

In an electric circuit closing switch of the character described, an elongated support, a spring arm extending lengthwise of the support and secured at one end thereto, a pointed contact secured on the free end of the spring arm, a cooperating contact member secured to the support and adapted to be engaged by the pointed contact, a pivot on said support, a. trigger lever mounted on said pivot, means on the trigger lever for engaging and securing the free end of the spring arm in a position Where the contacts are spaced apart, and a temperature actuated bimetallic strip mounted on said support and en gaging the trigger lever for pivoting the trigger' lever to release the spring arm so that the` pointed contact will dig into the surface of the: contact member.

LIZANDRO FERNANDEZ-CASTRO REFERENCES CITED The following references are of record in the? le of this patent:

UNITED STATES PATENTS Name Date v Foster Aug. 24, 1937 Acly et al. Jan. 25, 1944v Number 

